How does heat travel? and size so same heat is contained; spoons should be placed in cup at same time and left for the same length of time; spoons should be close to the same size. Note: Ensure students take care when feeling the metal spoon as it can become quite hot to touch.
Content focus: Heat travels by conduction, convection or radiation Identifying the difference between a thermal conductor and a thermal insulator Inquiry skills focus: Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating Background information
Answers Page 72 1. into, out 2. conduction, convection, radiation 3. (a) (ii) metal spoon should be ticked (b) Answers should indicate that metal is a good conductor of heat and the wood is not so the metal spoon will get hotter. 4. Answers should indicate that plastic does not let heat travel through easily so the handle will stay cool and not burn their hand. 5. insulator 6. a convection current 7. Answers should indicate we feel the sun’s heat because infrared heat rays radiate from the sun to Earth. Science as a Human Endeavour question Use and influence and science Good conductors are the metals tin, copper and steel. (The others are good insulators.)
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• Heat energy can be transferred in three ways: by radiation through infrared rays; by convection, which transfers heat through currents in liquids and gases; and by conduction, which moves heat from warmer to cooler areas in solid objects. Heat can only travel from warm to cooler areas and not the other way around. • Useful websites:
<http://spaceplace.jpl.nasa.gov/en/kids/st8/thermal_loop/index. shtml> (Powerpoint™ about heat travel)
Page 73
<http://www.bbc.co.uk/schools/ks2bitesize/science/materials/ keeping_warm/read1.shtml> (Information to read about temperature and insulating materials)
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The students should discover a metal spoon will be the best thermal conductor. Not only will it feel the hottest but the heat will remain there for the longest. If a ceramic spoon is used, they will find that spoon will hold less heat than the metal spoon but more than the plastic and wooden spoons. The plastic spoon will hold a slight amount of heat for a short time, while the wooden spoon will hold the least heat.
<http://www.sciencekids.co.nz/gamesactivities/keepingwarm.html> (Interactive activity investigating conductors and insulators)
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<http://www.kids-science-experiments.com/ heatconductorsandinsulators.html> (Information to read about conductors and insulators) Preparation
• Where possible, obtain the items described on page 71 to demonstrate to the students.
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• Organise the equipment needed for the experiments on page 73. The lessons
• Pages 71 and 72 should be used together. This unit is best covered after pages 66 to 69. The unit on pages 34 to 37 about investigating solids, liquids and gases should also be completed or revised.
Physical sciences
• Demonstrate how a metal spoon heats up in hot water/soup by conduction and how a plastic or wooden one does not. Discuss how the water/soup gradually heats up by convection and how stirring helps this process. • Students could work in pairs or a small group to complete page 73. However, ensure that all have the opportunity to feel and compare the heat of the spoons. • Discuss how a fair test can be achieved in the experiments on page 73; e.g. when comparing results from different groups of students doing this experiment, coffee cups used should be the same thickness AUSTRALIAN CURRICULUM SCIENCE
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